Numerical and Experimental Investigation on Hydrodynamic Characteristics of FLNG With an Account of the Inner-Tank Sloshing

FLNG is a new type of floating LNG platform which is ship-shaped FPSO hull equipped with LNG storage tanks and liquefaction plants and has been developed as an alternative to long pipelines to LNG liquefaction plant on land for stranded offshore fields. Different to the conventional FPSO, the hydrodynamic performance of the being-proposed FLNG can be significantly affected by the inner-tank liquid sloshing, due to the fact that LNG performs better liquidity than crude oil. In order to investigate the hydrodynamic characteristics of FLNG with large hull and high center of gravity, a series of numerical simulations on an FLNG designed by CNOOC and MARIC were conducted with the help of the well-known code WADAM. In addition, corresponding model tests on the same vessel with solid ballast were completed, serving as a verification of the numerical simulations. In order to inspect the sloshing effects of inner tanks on the global motion responses of the FLNG vessel, model tests with liquid ballast were also conducted. Comparisons were made between numerical and experimental results with methods of Fast Fourier Transformation technology and spectral analysis. The numerical simulation results were in good accordance with those of the model tests, which proves the feasibility of the numerical simulations. Furthermore, the effects of the inner tank sloshing on the FLNG hydrodynamic characteristics were summed up. Conclusions obtained from the comparison results would be of significant importance for the design of the FLNG system.

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Study on the Hydrodynamic Characteristics for Heave Plate Structure of Truss Spar

29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 6 ◽

10.1115/omae2010-21166 ◽

2010 ◽

Author(s):

Wenjun Shen ◽

Yougang Tang ◽

Liqin Liu

Keyword(s):

Numerical Simulations ◽

Forced Oscillation ◽

Hydrodynamic Performance ◽

Hydrodynamic Characteristics ◽

Hydrodynamic Coefficients ◽

Plate Structure ◽

Plate Spacing ◽

Mesh Method ◽

Truss Spar ◽

Heave Plate

The hydrodynamic characteristics of heave plates are studied in this paper. Firstly, different motion amplitudes and plate spacing influencing hydrodynamic coefficients are considered. Secondly, heave plates with different thicknesses are calculated, the case of edges with inclined form for heave plate is also taken into account. Numerical simulations are made for the plate forced oscillation, employing the dynamic mesh method and UDF (User defined functions). The values of Cm and Cd for heave plate are calculated. It is found that, in a certain amplitude range, Cm increases with increasing of amplitudes, Cd decreases with increasing of amplitudes. The values of Cm and Cd increase with increasing of plate spacing. Furthermore with the same effective thickness, the hydrodynamic performance of heave plate with inclined form is improved greatly.

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Study of Motion Performance of a Floating System With Four Moonpools and a VAWT

ASME 2021 3rd International Offshore Wind Technical Conference ◽

10.1115/iowtc2021-3511 ◽

2021 ◽

Author(s):

Lei Tan ◽

Satsuya Moritsu ◽

Tomoki Ikoma ◽

Yasuhiro Aida ◽

Koichi Masuda

Keyword(s):

Potential Theory ◽

Theoretical Calculations ◽

Model Tests ◽

Hydrodynamic Performance ◽

Linear Potential ◽

Gyroscopic Effect ◽

Floating Foundation ◽

Motion Responses ◽

Floating System ◽

Linear Potential Theory

Abstract In this paper the hydrodynamic performance of a barge-type floating foundation installed with four moonpools and a VAWT was investigated through model tests and theoretical calculations. The characteristics of wave-induced motion responses and tether tensions and the effects of turbine rotations were examined. Physical model tests were conducted in a wave tank using regular waves with the wave period ranging from 0.6 to 1.6 seconds and 0.01 or 0.02 meters in amplitude. A 2-MW-class VAWT was modelled with a scale ratio of 1/100 in the experiments. By varying the mass and the rotational speed of the turbine, gyroscopic moment effects were studied. In addition, numerical calculations based on the linear potential theory and Green function method were carried out to estimate motion responses and tether tensions. The present results indicate that the gyroscopic effect due to turbine rotations can be profound. It was found that the first-order motions of the floating system were substantially reduced by the gyroscopic effect, while the second-order motions and tether tensions may be significantly increased. Moreover, the viscous damping of water motions in moonpools was found not negligible. As a result, theoretical models based on linear potential theory should be used with care in hydrodynamic analysis with regard to the floating systems with VAWT rotations. In addition, the present in-house program code was validated against WAMIT through comparing hydrodynamic predictions of a floating foundation with four moonpools, with reasonable agreement.

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Analysis of tunnel hydrodynamic characteristics for planing trimaran by model tests and numerical simulations

Ocean Engineering ◽

10.1016/j.oceaneng.2015.12.038 ◽

2016 ◽

Vol 113 ◽

pp. 101-110 ◽

Cited By ~ 19

Author(s):

Yi Jiang ◽

Hanbing Sun ◽

Jin Zou ◽

Ankang Hu ◽

Jinglei Yang

Keyword(s):

Numerical Simulations ◽

Model Tests ◽

Hydrodynamic Characteristics

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Hydrodynamic characteristics of moored floating pipe breakwaters in random waves

Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment ◽

10.1243/147509003321921346 ◽

2003 ◽

Vol 217 (2) ◽

pp. 95-110 ◽

Cited By ~ 5

Author(s):

V Sundar ◽

R Sundaravadivelu ◽

S Purushotham

Keyword(s):

Hydrodynamic Performance ◽

Hydrodynamic Characteristics ◽

Random Waves ◽

Mooring Lines ◽

Reflection And Transmission ◽

Transmission Coefficients ◽

Motion Responses ◽

Analysis Of Results ◽

Mooring Forces ◽

Set Up

The hydrodynamic performance characteristics of a floating pipe breakwater (FPBW) model (row of pipes separated by a distance equivalent to the pipe diameter) moored to the flume floor with slack moorings has been investigated in random waves through an experimental programme. The tests have been conducted on three models each with pipes of different diameter. The average reflection and transmission coefficients are evaluated from measurements and reported as a function of relative breakwater width. The motion responses, as well as the variations in the forces on the seaside and lee side mooring lines, are also presented. In addition, statistical analysis has been carried out to prove that the heave and surge motions, as well as the peak mooring forces, follow the Raleigh distribution. The details of the models, set-up, experimental procedure and analysis of results are presented and discussed.

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Hydrodynamic Characteristics in Ecological Arc-Shaped Baffle Fishway

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.212-213.1119 ◽

2012 ◽

Vol 212-213 ◽

pp. 1119-1122 ◽

Cited By ~ 1

Author(s):

Fei Yu ◽

Jia Yuan Wang ◽

Li Quan Xie

Keyword(s):

Water Flow ◽

Model Tests ◽

Experimental Results ◽

Hydraulic Structures ◽

Hydrodynamic Characteristics ◽

Upstream Migration ◽

Migratory Fish ◽

Influence Of Water ◽

New Type ◽

Main Components

Fishways are hydraulic structures allowing fishes upstream migration through engineering constructions in the rivers. The Denil type has a wide application and the main components are flat baffles. In this paper, we present a new type of baffle (arc-shaped baffle) to ameliorate the hydrodynamic characteristics in the fishway. The main improvement of arc-shaped baffle fishway is the alteration that the flat baffles are replaced by arc-baffles. In order to investigate the influence of water flow on migratory fish in the arc-baffle fishway, model tests were conducted. Based on the experimental results, the conclusion can be reached that hydrodynamic characteristics in arc-shaped baffle fishways are steadier than that in traditional Denil fishways, which makes fishes ascend easily.

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Hydrodynamic Characteristics of Floating Pipes in Random Waves

Volume 5: Ocean Engineering ◽

10.1115/omae2013-10164 ◽

2013 ◽

Cited By ~ 1

Author(s):

Tiaojian Xu ◽

Guohai Dong ◽

Yunpeng Zhao ◽

Xiaozhou Ma ◽

Yuxiang Ma

Keyword(s):

Rayleigh Distribution ◽

Hydrodynamic Performance ◽

Experimental Program ◽

Hydrodynamic Characteristics ◽

Random Waves ◽

Mooring Lines ◽

Pipe Model ◽

Motion Responses ◽

Analysis Of Results ◽

Set Up

The hydrodynamic performance characteristics of a round floating pipe model moored to the flume floor with pre-tensioned moorings has been investigated in random waves through an experimental program. The details of the models, set-up, experimental procedure and analysis of results are presented and discussed. The drag coefficient of floating pipes in random waves are analyzed. The motion responses, as well as the variations in the forces on the seaside mooring lines, are presented. In addition, statistical analysis has been carried out to prove that the heave and surge motions, as well as the peak mooring forces, follow the Rayleigh distribution.

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Hydrodynamic characteristics of vertical and quadrant face pile supported breakwater under oblique waves

Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment ◽

10.1177/14750902211031353 ◽

2021 ◽

pp. 147509022110313

Author(s):

T J Jemi Jeya ◽

V Sriram ◽

V Sundar

Keyword(s):

Experimental Study ◽

Hydrodynamic Performance ◽

Hydrodynamic Characteristics ◽

Scattering Parameter ◽

Oblique Waves ◽

Test Conditions ◽

Relative Water ◽

Identical Test ◽

Run Up ◽

Water Depths

This paper presents the results from a comprehensive experimental study on the Quadrant Face Pile Supported Breakwater (QPSB) in two different water depths exposed to three different oblique wave attacks. The results are compared with that for a Vertical face Pile Supported Breakwater (VPSB) for identical test conditions. The paper compares the reflection coefficient, transmission coefficient, energy loss coefficient, non-dimensional pressure, and non-dimensional run-up as a function of the relative water depth and scattering parameter. The results obtained for QPSB are validated with existing results. The salient observations show that QPSB experiences better hydrodynamic performance characteristics than the VPSB under oblique waves.

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Effect of Geometric Parameters of New Semisubmersible Platform on Stability and Hydrodynamic Performance

10.1115/omae2021-63218 ◽

2021 ◽

Author(s):

Tianying Wang ◽

Yanjun Zhou ◽

Honglin Tang ◽

Shihua Zhang ◽

Haiqing Tian

Keyword(s):

Geometric Parameters ◽

Hydrodynamic Performance ◽

Geometrical Parameters ◽

Main Body ◽

Floating Bodies ◽

Full Picture ◽

New Type ◽

Design Plan ◽

The Stability ◽

Shape Characteristics

Abstract The JCSM concept (short for Jackup Combined Semisubmersible Multifunction Platform) is a new type of semisubmersible platform presented by the first author, which overcomes the shortcomings of the available semisubmersible platforms, and combines the advantages of the traditional semisubmersible platform, the Jackup platform and the new FPSO concept - IQFP. Due to the complicated interaction between stability and hydrodynamic performance, it is necessary to explore the effect of geometrical parameters of the main body on the stability and hydrodynamic performance in order to obtain the optimal design plan of a JCSM platform. Firstly, the structure components and innovations of the JCSM were briefly reviewed in order to facilitate readers to understand its full picture. Then, six independent geometric parameters were selected by carefully studying the shape characteristics of the initial design plan of a JCSM study case. Furthermore, the stability heights and motion responses of various floating bodies of the JCSM case with different geometric parameters in wave were calculated using boundary element method based on potential flow theory. Lastly, effect of the shape parameters on stability and hydrodynamic performance of the JCSM was qualitatively evaluated. The research would shed lights on the shape design of the JCSM main body.

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